package org.bouncycastle.asn1.pkcs;

import org.bouncycastle.asn1.ASN1Encodable;
import org.bouncycastle.asn1.ASN1EncodableVector;
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.ASN1TaggedObject;
import org.bouncycastle.asn1.DERNull;
import org.bouncycastle.asn1.DERObject;
import org.bouncycastle.asn1.DEROctetString;
import org.bouncycastle.asn1.DERSequence;
import org.bouncycastle.asn1.DERTaggedObject;
import org.bouncycastle.asn1.oiw.OIWObjectIdentifiers;
import org.bouncycastle.asn1.x509.AlgorithmIdentifier;

public class RSAESOAEPparams extends ASN1Encodable {
    private AlgorithmIdentifier hashAlgorithm;
    private AlgorithmIdentifier maskGenAlgorithm;
    private AlgorithmIdentifier pSourceAlgorithm;

    // BEGIN android-changed
    public final static AlgorithmIdentifier DEFAULT_HASH_ALGORITHM = new AlgorithmIdentifier(
            OIWObjectIdentifiers.idSHA1, DERNull.INSTANCE);
    // END android-changed
    public final static AlgorithmIdentifier DEFAULT_MASK_GEN_FUNCTION = new AlgorithmIdentifier(
            PKCSObjectIdentifiers.id_mgf1, DEFAULT_HASH_ALGORITHM);
    public final static AlgorithmIdentifier DEFAULT_P_SOURCE_ALGORITHM = new AlgorithmIdentifier(
            PKCSObjectIdentifiers.id_pSpecified,
            new DEROctetString(new byte[0]));

    public static RSAESOAEPparams getInstance(Object obj) {
        if (obj instanceof RSAESOAEPparams) {
            return (RSAESOAEPparams) obj;
        } else if (obj instanceof ASN1Sequence) {
            return new RSAESOAEPparams((ASN1Sequence) obj);
        }

        throw new IllegalArgumentException("unknown object in factory: "
                + obj.getClass().getName());
    }

    /**
     * The default version
     */
    public RSAESOAEPparams() {
        hashAlgorithm = DEFAULT_HASH_ALGORITHM;
        maskGenAlgorithm = DEFAULT_MASK_GEN_FUNCTION;
        pSourceAlgorithm = DEFAULT_P_SOURCE_ALGORITHM;
    }

    public RSAESOAEPparams(AlgorithmIdentifier hashAlgorithm,
            AlgorithmIdentifier maskGenAlgorithm,
            AlgorithmIdentifier pSourceAlgorithm) {
        this.hashAlgorithm = hashAlgorithm;
        this.maskGenAlgorithm = maskGenAlgorithm;
        this.pSourceAlgorithm = pSourceAlgorithm;
    }

    public RSAESOAEPparams(ASN1Sequence seq) {
        hashAlgorithm = DEFAULT_HASH_ALGORITHM;
        maskGenAlgorithm = DEFAULT_MASK_GEN_FUNCTION;
        pSourceAlgorithm = DEFAULT_P_SOURCE_ALGORITHM;

        for (int i = 0; i != seq.size(); i++) {
            ASN1TaggedObject o = (ASN1TaggedObject) seq.getObjectAt(i);

            switch (o.getTagNo()) {
                case 0:
                    hashAlgorithm = AlgorithmIdentifier.getInstance(o, true);
                    break;
                case 1:
                    maskGenAlgorithm = AlgorithmIdentifier.getInstance(o, true);
                    break;
                case 2:
                    pSourceAlgorithm = AlgorithmIdentifier.getInstance(o, true);
                    break;
                default:
                    throw new IllegalArgumentException("unknown tag");
            }
        }
    }

    public AlgorithmIdentifier getHashAlgorithm() {
        return hashAlgorithm;
    }

    public AlgorithmIdentifier getMaskGenAlgorithm() {
        return maskGenAlgorithm;
    }

    public AlgorithmIdentifier getPSourceAlgorithm() {
        return pSourceAlgorithm;
    }

    /**
     * <pre>
     *  RSAES-OAEP-params ::= SEQUENCE {
     *     hashAlgorithm      [0] OAEP-PSSDigestAlgorithms     DEFAULT sha1,
     *     maskGenAlgorithm   [1] PKCS1MGFAlgorithms  DEFAULT mgf1SHA1,
     *     pSourceAlgorithm   [2] PKCS1PSourceAlgorithms  DEFAULT pSpecifiedEmpty
     *   }
     *  
     *   OAEP-PSSDigestAlgorithms    ALGORITHM-IDENTIFIER ::= {
     *     { OID id-sha1 PARAMETERS NULL   }|
     *     { OID id-sha256 PARAMETERS NULL }|
     *     { OID id-sha384 PARAMETERS NULL }|
     *     { OID id-sha512 PARAMETERS NULL },
     *     ...  -- Allows for future expansion --
     *   }
     *   PKCS1MGFAlgorithms    ALGORITHM-IDENTIFIER ::= {
     *     { OID id-mgf1 PARAMETERS OAEP-PSSDigestAlgorithms },
     *    ...  -- Allows for future expansion --
     *   }
     *   PKCS1PSourceAlgorithms    ALGORITHM-IDENTIFIER ::= {
     *     { OID id-pSpecified PARAMETERS OCTET STRING },
     *     ...  -- Allows for future expansion --
     *  }
     * </pre>
     * 
     * @return the asn1 primitive representing the parameters.
     */
    public DERObject toASN1Object() {
        ASN1EncodableVector v = new ASN1EncodableVector();

        if (!hashAlgorithm.equals(DEFAULT_HASH_ALGORITHM)) {
            v.add(new DERTaggedObject(true, 0, hashAlgorithm));
        }

        if (!maskGenAlgorithm.equals(DEFAULT_MASK_GEN_FUNCTION)) {
            v.add(new DERTaggedObject(true, 1, maskGenAlgorithm));
        }

        if (!pSourceAlgorithm.equals(DEFAULT_P_SOURCE_ALGORITHM)) {
            v.add(new DERTaggedObject(true, 2, pSourceAlgorithm));
        }

        return new DERSequence(v);
    }
}
